Charge-generating thread for bacterium-countermeasure, cloth for bacterium-countermeasure, cloth, clothing article, medical member, charge-generating thread that acts on living body, and charge-generating thread for substance-adsorption

ABSTRACT

A piezoelectric thread that includes a core thread; and a piezoelectric film wound around the core thread. The piezoelectric thread is constructed to generate a charge by energy imparted from outside of the piezoelectric thread.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of application Ser. No.16/183,884, filed Nov. 8, 2018, which is a continuation of Internationalapplication No. PCT/JP2017/017237, filed May 2, 2017, which claimspriority to International application No. PCT/JP2016/082416, filed Nov.1, 2016, and International application No. PCT/JP2016/066749, filed Jun.6, 2016, the entire contents of each of which are incorporated herein byreference.

FIELD OF THE INVENTION

The present invention relates to a thread having antibacterial property;and a cloth, a clothing article, or a medical member in which the threadis used.

BACKGROUND OF THE INVENTION

Many suggestions have been presented regarding fibrous materials havingantibacterial properties (see Patent Documents 1 to 7).

-   Patent Document 1: Japanese Patent No. 3281640-   Patent Document 2: Japanese Patent Application Laid-Open (JP-A-) No.    H07-310284-   Patent Document 3: Japanese Patent No. 3165992-   Patent Document 4: Japanese Patent No. 1805853-   Patent Document 5: JP-A No. H08-226078-   Patent Document 6: JP-A No. H09-194304-   Patent Document 7: JP-A No. 2004-300650

SUMMARY OF THE INVENTION

However, the antibacterial effect of such materials has not been able tobe sustained over a long term.

Moreover, materials having antibacterial property may cause anallergenic reaction by, for example, a chemical agent contained therein.

Thus, an object of this invention is to provide a charge-generatingthread for bacterium-countermeasures which sustains an advantageouseffect thereof over a longer period than conventional materials havingantibacterial property, and which is further higher in safety thanchemical agents and others.

The charge-generating thread according to an aspect of the presentinvention includes a charge-generating fiber. The charge-generatingfiber generates a charge by energy applied from the outside of thefiber.

It has been hitherto known that the proliferation of bacillus and fungican be restrained by an electric field (see, for example, TetsuakiTsuchido, Hiroki Kourai, Hideaki Matsuoka and Junichi Koizumi,“Microorganism Control—Science and Engineering, published by KodanshaLtd.; and Koichi Takagi, “Application of High-Voltage Plasma Techniqueto Agricultural and Food Fields”, J. HTSJ, vol. 51, No. 216). Moreover,an electric potential which generates this electric field may cause acurrent to flow in a current path made by, for example, moisture, and ina circuit formed by, for example, a local microscopic dischargephenomenon. This current would weaken bacteria to restrain theproliferation of the weakened bacteria. The charge-generating thread forbacterium-countermeasure according to an aspect of the present inventionhas a charge-generating fiber, which generates a charge by energyapplied from the outside of the fiber. Thus, when the thread approachesor contacts gaps between thread lines or a human body or any otherobject that has a predetermined electric potential (examples thereofincluding the ground potential), the thread generates an electric field.Alternatively, when the charge-generating thread forbacterium-countermeasure of the present invention approaches or contactsgaps between thread lines or a human body or any other object that has apredetermined electric potential (examples thereof including the groundpotential) through sweat or any other water content, the thread causes acurrent to flow therein.

Accordingly, the charge-generating thread for bacterium-countermeasureaccording to an aspect of the present invention exhibits anantibacterial effect (effect of restraining the generation of bacteria)or a sterilizing effect (effect of sterilizing or killing bacteria) forreasons described below. When this thread is applied to any member thatis used in the state of approaching or contacting a human body or anyother object that has a predetermined electric potential (the member: aclothing article, a footwear article, or a medical article such as aface mask), an electric field or current is generated. By a directioneffect of the electric field or current, problems are caused in cellmembranes of bacteria, or electron transport systems of bacteria forlife support, so that the bacteria are sterilized or the bacteriathemselves are weakened. Furthermore, the electric field or current maychange oxygen contained in water content to an active oxygen species.Alternatively, oxygen radials may be produced in cells of the bacteriaby a stress environment based on the presence of the electric field orcurrent; the bacteria are sterilized or weakened through the effects ofthe active oxygen species containing these radials. Moreover, thesereasons may be combined with each other to generate an antibacterialeffect or sterilizing effect.

It is conceivable that the charge-generating fiber, which generates acharge by an energy from the outside of the fiber, is, for example, afiber making use of, for example, a substance having a photoelectriceffect, a substance having pyroelectric effect, or a piezoelectricsubstance. The following structure also forms a charge-generating fiber:a structure in which an electroconductive body is used as a core thread,an insulator is wound on the electroconductive body, and further avoltage is applied to the electroconductive body to generate a charge.

When the piezoelectric substance is used, piezoelectricity generates anelectric field so that no power source is required and no electric shockis favorably caused. Moreover, the lifespan of the piezoelectricsubstance is sustained longer than the period of an antibacterial effectof any chemical agent or the like. Furthermore, the piezoelectricsubstance is less likely to cause a risk of generating an allergenicreaction than any chemical agent.

The following cloth also can individually generate an electric field ora current to produce an antibacterial effect: a cloth including a firstcharge-generating fiber that generates a positive charge and a secondcharge-generating fiber that generates a negative charge.

Aspects of the present invention make it possible to realize acharge-generating thread for bacterium-countermeasure which sustains anadvantageous effect thereof over a longer period than conventionalmaterials having antibacterial property, and which is further higher insafety than chemical agents and others.

BRIEF EXPLANATION OF THE DRAWINGS

FIG. 1(A) is a view illustrating a structure of a piezoelectric thread1, and FIG. 1(B) is a plan view of a piezoelectric film 10.

FIGS. 2(A) and 2(B) are views showing relationships among a monoaxiallydrawn direction of polylactic acid, the direction of an electric fieldto the acid, and the deformation of a piezoelectric film 10.

FIG. 3 is a view illustrating the piezoelectric thread 1 to whichexternal force is applied.

FIG. 4(A) is a schematic plan view of a cloth 100, and FIG. 4(B) is aview illustrating an arrangement of individual lines of the thread.

FIG. 5 is a view illustrating a structure of a piezoelectric thread 2.

FIG. 6(A) is a schematic plan view of a cloth 100A, and FIG. 6(B) is aview illustrating an electric field generated between individual linesof threads.

FIG. 7 is a view illustrating electric fields generated betweenindividual lines of threads.

FIG. 8(A) is a partial exploded view illustrating a structure of apiezoelectric thread 31, and FIG. 8(B) is a partial exploded viewillustrating a structure of a piezoelectric thread 32.

FIG. 9(A) is a partial exploded view illustrating a structure of apiezoelectric thread 33, and FIG. 9(B) is a partial exploded viewillustrating a structure of a piezoelectric thread 34.

FIG. 10 is a view illustrating a gap between portions of a piezoelectricfilm 10 exaggeratedly in the piezoelectric thread 33.

FIG. 11 is a partial exploded view illustrating a structure of apiezoelectric thread 35.

FIG. 12 is a view illustrating a structure of a braid.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1(A) is a partial exploded view illustrating a structure of apiezoelectric thread 1, and FIG. 1(B) is a plan view of a piezoelectricfilm 10. The piezoelectric thread 1 is an example of a charge-generatingfiber that generates a charge by an energy from the outside of thefiber.

The piezoelectric thread 1 is a thread in which the piezoelectric film10 is wound on a core thread 11. The piezoelectric film 10 is an exampleof a piezoelectric substance. The core thread 11 is appropriatelyselected from any natural fiber or chemical fiber. Examples of thenatural fiber include plant fiber, animal fiber, and polylactic acid.Examples of the plant fiber include cotton, and hemp. When polylacticacid is used as the core thread 11, it is unnecessary that the corethread 11 is piezoelectric polylactic acid. As will be detailed later,when polylactic acid is used for the piezoelectric film 10, the film 10and the core thread 11 are identical with each other in material, sothat these two 10 and 11 are high in affinity with each other. Examplesof the chemical fiber include the synthetic fiber, glass fiber, andcarbon fiber. The chemical fiber is stronger than the natural fiber.

The core thread 11 may be an electroconductive thread, which haselectroconductivity. In the case of rendering the core thread 11 anelectroconductive thread, at the time of inspecting the piezoelectricityof the piezoelectric thread 1, a measurement can be made about chargesgenerated in the piezoelectric thread 1, using the core thread 11 andelectrodes formed on portions of the outer circumference of thepiezoelectric thread 1. This makes it possible to inspect thepiezoelectric performance of the piezoelectric film 10 used in thepiezoelectric thread 1. By short-circuiting lines of theelectroconductive thread with each other, a circuit is evidently formedbetween any two of the lines so that an electric field generated betweensurfaces of the individual lines is dramatically increased. Moreover, inthe use of an electroconductive body for the core thread 11, when acurrent is caused to flow into the core thread 11, a thread in which acharge is generated by an energy from the outside can be realized evenby a structure in which an insulator other than the piezoelectric film10 is wound on the core thread 11.

The core thread 11 is not an essential member. Even when the core thread11 is not used, a piezoelectric thread (spiral thread) can be gained byturning the piezoelectric film 10 spirally. When the core thread 11 isnot used, the spiral thread becomes a hollow thread to be improved intemperature-keeping power. When the spiral thread itself is impregnatedwith an adhesive agent, the resultant can be improved in strength.

The piezoelectric film 10 is made of, for example, a piezoelectricpolymer. Piezoelectric films can be classified into films havingpyroelectricity, and films having no pyroelectricity. For example, PVDF(polyvinylidene fluoride) is pyroelectric to generate charges also by achange in temperature. In PVDF or any other piezoelectric substancehaving pyroelectricity, charges are generated in its surface also bythermal energy from a human body.

Polylactic acid (PLA) is a piezoelectric film having no pyroelectricity.Polylactic acid is monoaxially drawn to generate piezoelectricity.Polylactic acid can be divided to PLLA, which is obtained bypolymerizing an L-body monomer, or PDLA, which is obtained bypolymerizing a D-body monomer.

Polylactic acid is a chiral polymer, and its main chain has a spiralstructure. When polylactic acid is monoaxially drawn to orient moleculesthereof, the polymer expresses piezoelectricity. When the polymer isfurther subjected to thermal treatment to be heightened incrystallization degree, the polymer is made high in piezoelectricconstant. About the piezoelectric film 10 made of monoaxially drawnpolylactic acid, the thickness direction thereof and a drawn direction900 thereof are defined as a first axis and a third axis of the film,respectively, and further the direction orthogonal to both of the firstaxis and the third axis is defined as a second axis of the film. In thiscase, the piezoelectric film 10 has tensor components d₁₄ and d₂₅ aspiezoelectric strain constants. Accordingly, when polylactic acid isstrained along a direction of 45° angle to the monoaxially drawndirection, charges are generated.

FIGS. 2(A) and 2(B) are views showing relationships among themonoaxially drawn direction of polylactic acid, the direction of anelectric field to the acid, and deformation of the piezoelectric film10. As illustrated in FIG. 2(A), when the piezoelectric film 10contracts in the direction of a first diagonal line 910A and furtherexpands in the direction of a second diagonal line 910B, which isorthogonal to the first diagonal line 910A, an electric field isgenerated in a direction from the rear side of the paper surface of FIG.2(A) to the front side thereof. In short, in the piezoelectric film 10,negative charges are generated on the front side of the paper surface.As illustrated in FIG. 2(B), also when the piezoelectric film 10 expandsin the direction of the first diagonal line 910A and further contractsin the direction of the second diagonal line 910B, charges aregenerated. However, the polarity thereof is reverse to the above. Thus,an electric field is generated in the direction from the front side ofthe paper surface toward the rear side thereof. In short, in thepiezoelectric film 10, positive charges are generated on the front sideof the paper surface.

Polylactic acid is subjected to molecular-orientating treatment based ondrawing to generate piezoelectricity. Thus, the acid is not required tobe subjected to polling treatment, unlike other piezoelectric polymerssuch as PVDF, or piezoelectric ceramics. The piezoelectric constant ofmonoaxially drawn polylactic acid is from about 5 to 30 pC/N to be avery high piezoelectric constant out of respective piezoelectricconstants of polymers. Furthermore, the piezoelectric constant ofpolylactic acid is not varied with time to be very stable.

The piezoelectric film 10 is produced by cutting out a monoaxially drawnpolylactic acid sheet as described above into a width of about 0.5 to 2mm. As illustrated in FIG. 1(B), about the piezoelectric film 10, thelong axis direction thereof is consistent with the drawn direction 900.As shown in FIG. 1(A), the piezoelectric film 10 turns into thepiezoelectric thread 1 of a leftward spiraled thread (hereinafterreferred to as an S thread), which has been leftward spiraled onto thecore thread 11, so as to be twisted. The drawn direction 900 is in thestate of being inclined leftward at an angle of 45 degrees to the axialdirection of the piezoelectric thread 1.

As illustrated in FIG. 3, therefore, when external force (e.g., tension)is applied to the piezoelectric thread 1, the piezoelectric film 10turns into a state illustrated in FIG. 2(A) to generate, on the surfacethereof, negative charges.

When external force is applied to the piezoelectric thread 1 in such away, negative charges are generated on the surface thereof and positivecharges are generated inside the thread. Consequently, in thepiezoelectric thread 1, an electric field is generated by a potentialdifference generated by the charges. This electric field leaks into anear space to form together with the other spatial portion a bondedelectric field. Moreover, when the piezoelectric thread 1 approaches orcontacts a near human body or any other near object having apredetermined electric potential (examples thereof including the groundpotential), the potential generated in the piezoelectric thread 1 causesthe generation of an electric field between the thread and the object.

It has been hitherto known that the proliferation of bacillus and fungican be restrained by an electric field (see, for example, TetsuakiTsuchido, Hiroki Kourai, Hideaki Matsuoka and Junichi Koizumi,“Microorganism Control—Science and Engineering, published by KodanshaLtd.; and Koichi Takagi, “Application of High-Voltage Plasma Techniqueto Agricultural and Food Fields”, J. HTSJ, vol. 51, No. 216). Moreover,an electric potential which generates the electric field may cause acurrent to flow in a current path made by, for example, moisture, and ina circuit formed by, for example, a local microscopic dischargephenomenon. This current would weaken the bacteria to restrain theproliferation of the bacteria. Examples of the bacteria referred to inthe present embodiment include bacillus, fungi, mites, fleas, and otherfine- or micro-organisms.

Accordingly, the piezoelectric thread 1 directly exhibits anantibacterial effect or sterilizing effect by an electric field creatednear the piezoelectric thread 1 or by an electric field generated whenthe piezoelectric thread 1 approaches or contacts a human body or anyother object having a predetermined electric potential. Alternatively,when the piezoelectric thread 1 approaches or contacts a different fibernear this thread, or a human body or any other object that has apredetermined electric potential through sweat or any other watercontent, the thread causes a current to flow therein. Also by thecurrent, this thread may directly exhibit an antibacterial effect orsterilizing effect. Alternatively, the thread may indirectly exhibit anantibacterial effect or sterilizing effect through active oxygen speciesobtained by a change of oxygen contained in water content by effect ofthe current or voltage, and through radical oxygen species or otherantibacterial chemical species (such as amine derivatives) generated byinteraction with an additive contained in the fiber or generated by acatalytic effect. Alternatively, oxygen radials may be produced in cellsof the bacteria by a stress environment based on the presence of theelectric field or current. In this way, the piezoelectric thread 1 mayindirectly exhibit an antibacterial effect or sterilizing effect. As theradicals, super oxide anion radicals (active oxygen) or hydroxy radicalswould be generated.

A charge-generating thread as described above including acharge-generating fiber, which generates a charge by an energy from theoutside, may be applied to various articles of clothing, medicalmembers, and other products. The charge-generating thread is applicableto, for example, any one of the following: underclothes (particularly,socks), towels, insoles for shoes, boots and others, entire sportsclothes, hats and caps, bedclothes (such as futons (Japanesebedclothes), mattresses, bed sheets, pillows, and pillow covers),toothbrushes, flosses, various filters (such as filters for waterpurifiers, air conditioners, and air cleaners), stuffed toys,pet-related goods (mats for pets, clothing articles for pets, and innersfor pet clothing articles), various mat articles (legs, hands, andlavatory seats), curtains, kitchen utensils (such as sponges and dishtowels), seats (seats for automobiles, electric trains, airplanes, andothers), buffer materials and exterior materials for helmets formotorcycles, sofas, bandages, gauze pieces, masks, suture threads,clothing articles for doctors and patients, supporters, sanitaryarticles, sports goods (such as wears, inners for gloves, and gauntletsused in martial arts), and packing materials.

Out of clothing articles, particularly, socks (or supporters) areindispensably contracted by walking or some other motion of the user,along his/her joint, so that the piezoelectric thread 1 generatescharges at a high frequency. Moreover, socks absorb sweat or any otherwater content to become a hotbed for the proliferation of bacteria.However, the piezoelectric thread 1 can restrain the proliferation ofbacteria to produce a remarkable advantageous effect forbacterium-countermeasure-articles for deodorization.

Moreover, the present invention is usable to restrain bacteria on bodysurfaces of an animal other than humans. It is allowable to arrange apiezoelectric-substance-containing cloth onto at least one region ofskin of the animal to face the region, and restrain the proliferation ofbacteria on the body surface of the animal, which faces the cloth, byelectric charges generated when an external force is applied onto thepiezoelectric substance. This case makes it possible to restrain theproliferation of the bacteria on the body surface of the animal and curethe body surface of the animal from Trichophyton in a simple and easymanner that is higher in safety than the manner of using any medicine orthe like.

A cloth 100 into which the piezoelectric thread 1 is woven alsofunctions as a cloth for bacterium-countermeasure. FIG. 4(A) is aschematic plan view of the cloth 100, and FIG. 4(B) is a viewillustrating an arrangement of individual lines of the thread. The cloth100 is a cloth in which lines of a piezoelectric thread (first thread)1, lines of an ordinary thread 3, and lines of an electroconductivethread (second thread) 5 are woven into each other. The ordinary thread3 is a thread to which a piezoelectric substance is not fitted, andcorresponds to a dielectric substance. As described above, the ordinarythread 3 is made of a natural fiber or chemical fiber. However, theordinary thread 3 is not an essential constituent for the presentinvention.

The electroconductive thread 5, which is the second thread, is made ofan electroconductive substance (electroconductive fiber). Theelectroconductive fiber may be, for example, a fiber plated with carbon,a metal itself (fine wire), a slit ribbon, a polyester fiber having anelectroless-plated surface, or a product obtained by making a polyesterfilm having vapor-deposited electrodes into a slit ribbon form.

The electroconductive thread 5 is an electroconductive substance to havea predetermined uniform electric potential (examples thereof includingthe ground potential). The lines of the piezoelectric thread 1 arearranged, by a predetermined distance, apart from the lines of theelectroconductive thread 5 to interpose therebetween one or more of thelines of the ordinary thread 3, which corresponds to a dielectricsubstance. In a case where this electroconductive thread 5 has aforcibly fixed potential, such as the ground potential, at the time ofapplying external force to the piezoelectric thread 1, a potentialdifference between the electroconductive thread 5, which has thepredetermined electric potential, and the piezoelectric thread 1, whichgenerates electric charges, causes the generation of an electric fieldbetween the two. However, the ordinary thread 3 is not an essentialconstituent. Even when the ordinary thread 3 is not used, an electricfield is generated between the piezoelectric thread 1 and theelectroconductive thread 5. The electroconductive thread 5 may fulfil arole as a reference potential line. For example, when electric chargesare generated in the piezoelectric thread 1, a potential differencedistribution is generated in a cross section of the thread. In the crosssection, at its region near the electroconductive thread 5 the potentialthereof is defined as the reference potential. At a region distanttherefrom, a potential difference is generated from the referencepotential correspondingly to the electric charges generated therein.This potential is a potential relative to the reference potential. Whena potential difference is evidently defined not only inside thepiezoelectric thread but also in the space, an electric field is createdcorrespondingly to this potential difference. In this way, an electricfield may be formed between lines of the piezoelectric thread 1.Considering this matter, it is not desirable to arrange theelectroconductive thread 5 in such a manner that the potential generatedtherein is cancelled by the shift of the electric charges. Specifically,under conditions that any ordinary thread 3 is omitted in FIG. 4(B), thearrangement of thread lines are preferably an arrangement in which thefollowing lines are located in an order described herein: anelectroconductive thread line, a piezoelectric thread line, apiezoelectric thread line, an electroconductive thread line, apiezoelectric thread line, a piezoelectric thread line, and anelectroconductive thread line. Moreover, preferably, theelectroconductive thread lines are short-circuited to each other andmade equal in potential to each other. Furthermore, preferably, with anyadjacent two of the piezoelectric thread lines, polarities of electriccharges generated on their outsides in response to external force arereverse to each other. When an external force is applied to thearrangement, the arrangement causes the generation of a clear potentialdifference between any near two or contacting two of the piezoelectricthread lines so that an electric field is generated. WO 2015/159832publicly discloses a transducer in which a plurality of piezoelectricthread lines and a plurality of electroconductive thread lines are usedto produce a knitting or woven fabric, and the fact that a displacementis given to this knitting or fabric is sensed. In this case, all theelectroconductive thread lines are connected to a detecting sensor. Forany one of the piezoelectric thread lines, paired electroconductivethread lines, out of the electroconductive thread lines, are inevitablypresent. When electric charges are generated in the piezoelectric threadline, the electric charges are shifted in the electroconductive threadlines to neutralize the generated electric charges immediately. Thedetecting circuit detects an electric current based on this electronshift to output a signal. Accordingly, in this case, the generatedpotential is immediately cancelled; therefore, the following is notcaused: a strong electric field is created between the piezoelectricthread line and the electroconductive thread lines, or between thepiezoelectric thread line and any one of the other piezoelectric threadlines. Consequently, no antibacterial effect is exhibited.

The lines of the piezoelectric thread 1 are arranged very closely tothose of the electroconductive thread 5 so that the distancetherebetween is approximately zero. The intensity of any electric field,as is represented by E=V/d, becomes larger in inverse proportion to thedistance between substances generating charges. Thus, the intensity ofthe electric field generated by the cloth 100 becomes a very largevalue. This electric field is created by mutual bonding between electricfields generated inside the lines of the piezoelectric thread 1 andelectric fields generated inside lines of a piezoelectric thread 2. Asthe case may be, by water content containing an electrolyte such assweat, a circuit may be formed as an actual current path. In a cloth inwhich filaments of a fiber are knitted, fiber filaments arecomplicatedly entangled with each other, so that a case may be generatedwhere an electric field generated in one portion of the lines of thepiezoelectric thread 1 is mutually bonded to an electric field generatedin another portion of those of the piezoelectric thread 1. In the samemanner, a case may be generated where an electric field generated in oneportion of the lines of the piezoelectric thread 2 is mutually bonded toan electric field generated in another portion of those of thepiezoelectric thread 2. Even when the intensity of the electric field ismacroscopically zero or very weak, the electric field may bemicroscopically an aggregate of intense electric fields having vectordirections reverse to each other. About these phenomena, substantiallythe same description can be made even in a cloth made only of thepiezoelectric thread 1, a cloth made only of the piezoelectric thread 2,or a cloth made by weaving, into the piezoelectric thread(s) 1 and/or 2,an ordinary thread or electroconductive thread simultaneously.

Thus, the cloth 100 functions as a cloth generating an electric field.In the cloth 100, a current may flow between the lines of thepiezoelectric thread 1 and the lines of the electroconductive thread 5through water content such as sweat. Also by this current, the cloth mayalso exhibit an antibacterial effect or sterilizing effect.Alternatively, the cloth may indirectly exhibit an antibacterial effector sterilizing effect through active oxygen species obtained by a changeof oxygen contained in water content by the current or voltage, andthrough radical species or other antibacterial chemical species (such asamine derivatives) generated by interaction with an additive containedin the fiber or by a catalytic effect. Alternatively, oxygen radials maybe produced in cells of bacteria by a stress environment based on thepresence of the electric field or current. In this way, an antibacterialeffect or sterilizing effect may be indirectly exhibited.

The cloth 100 exhibits an antibacterial effect or sterilizing effect byan electric field which the cloth itself generates and a change in theintensity thereof, or by the current. Alternatively, the cloth exhibitsan antibacterial effect or sterilizing effect by, for example, radicalspecies generated by effect of the current or voltage.

Furthermore, when the electroconductive thread 5 elutes out therefrom ametal ion (such as Ag⁺, Zn²⁺ or Cu²⁺), the metal ion eluted out from theelectroconductive thread 5 makes the antibacterial effect or sterilizingeffect higher. In the cloth 100, even when the lines of thepiezoelectric thread 1 have spots from which no charge is generated,charges generated locally by the electroconductive thread 5 are carriedto the whole of the cloth so that the cloth wholly exhibits anantibacterial effect or sterilizing effect. Moreover, when theelectroconductive thread 5 is connected to a measuring instrument suchas an oscilloscope, it can be examined whether or not the piezoelectricthread 1 functions (whether or not charges are generated) (for example,delivery inspection can be made). When an electroconductive body fromwhich a metal ion elutes out is used for the core thread 11, the corethread 11 functions as an electroconductive fiber from which a metal ionelutes out. Thus, it is unnecessary to set any electroconductive threadseparately from the piezoelectric thread 1.

As described above, for example, a clothing article or medical member inwhich the cloth 100 is used exhibits an antibacterial effect orsterilizing effect. The piezoelectric thread used in the cloth 100 maybe a rightward spiraled piezoelectric thread 2 (hereinafter referred toas a Z thread) as illustrated in FIG. 5. Since the piezoelectric thread2 is the Z thread, the drawn direction 900 thereof is in the state ofbeing inclined rightward at an angle of 45 degrees to the axialdirection of the piezoelectric thread 1. Accordingly, when externalforce is applied to the piezoelectric thread 2, the piezoelectric film10 turns into a state illustrated in FIG. 2(B) to generate, on thesurface thereof, positive charges. Thus, when the piezoelectric thread 2also approaches or contacts a human body or any other object that has apredetermined electric potential (examples thereof including the groundpotential), the thread generates an electric field. Alternatively, whenthe piezoelectric thread 2 approaches or contacts a human body or anyother object that has a predetermined electric potential (examplesthereof including the ground potential) through sweat or any other watercontent, the thread causes a current to flow therein.

Any one of the piezoelectric threads is produced by any known method.For example, the following method is adoptable: a method of extrudingand shaping, for example, a piezoelectric polymer to be made into afibrous form as a fiber, as well as a covering thread including a slitfilm; a method of melt-spinning a piezoelectric polymer to be made intoa fibrous form (for example, a spinning and drawing method in which aspinning step and a drawing step are performed separately from eachother, a direct drawing method in which a spinning step and a drawingstep are linked to each other, a POY-DTY method in which a falsetwisting step can also be attained at the same time, or a super highspeed spinning method in which the spinning speed is made high); amethod of dry- or wet-spinning a piezoelectric polymer to be made into afibrous form (for example, a phase-separating method or dry- orwet-spinning method of dissolving a polymer, which is a raw material,into a solvent, and extruding out the solution through a nozzle to bemade into a fibrous form, a liquid crystal spinning method of making apolymer into a gel form in the state the polymer contains a solvent, soas to be evenly made into a fibrous form, or a liquid crystal spinningmethod of using a solution of a liquid crystal or a melted body thereofto make the liquid crystal into a fibrous form); or a method of spinninga piezoelectric polymer electrostatically to be made into a fibrousform.

Many bacteria have negative charges. Thus, the cloth having thepiezoelectric thread 2 can adsorb a great number of bacteria throughgenerated positive charges. Moreover, the cloth having the piezoelectricthread 2 can inactivate bacteria having negative charges through thegenerated positive charges. In such a way, a cloth using a piezoelectricthread generating, on the surface thereof, positive charges has a greatadvantageous effect as a piezoelectric thread forbacterium-countermeasure.

The piezoelectric thread 1 or 2 (or the cloth having at least one of thepiezoelectric threads 1 and 2) has use purposes described below besidesthe bacterium-countermeasure purpose.

(1) Piezoelectric Thread that Acts on a Living Body

Many tissues which are included in a living body have piezoelectricity.For example, collagen, which is included in a human body, is a kind ofprotein. Collagen is included in, for example, blood vessels, coria,ligaments, tendons, bones or cartilages in a large proportion. Collagenis a piezoelectric substance, so that a tissue in which collagen isoriented may show a very large piezoelectricity. About thepiezoelectricity of bones, many reports have been already made (see, forexample, Eiichi Sakata, “Piezoelectricity of Biopolymer”, Polymer vol.16 (1967), No. 9, pp. 795-800). Accordingly, when an electric field isgenerated by the cloth having the piezoelectric thread 1 or 2 and thenthe electric field is alternated or is changed in intensity, thepiezoelectric substance of the living body is vibrated by a reversepiezoelectric effect. The alternated electric field generated by thepiezoelectric thread(s) 1 and/or 2, or the electric field intensitychange applies micro-vibration to a part of the living body, forexample, capillary blood vessels or the corium thereof, so that animprovement of blood flow in the part can be promoted. This may promotethe recovery of, for example, skin diseases or injuries. Accordingly,the piezoelectric thread functions as a piezoelectric thread that actson a living body. WO 2015/159832 publicly discloses a transducer inwhich a plurality of piezoelectric thread lines and a plurality ofelectroconductive thread lines are used to produce a knitting or wovenfabric, and the fact that a displacement is given to this knitting orfabric is sensed. In this case, all the electroconductive thread linesare connected to a detecting sensor. For any one of the piezoelectricthread lines, paired electroconductive thread lines, out of theelectroconductive thread lines, are inevitably present. When electriccharges are generated in the piezoelectric thread line, the electriccharges are shifted in the electroconductive thread lines to neutralizethe generated electric charges immediately. The detecting circuitdetects an electric current based on this electron shift to output asignal. Accordingly, in this case, the generated potential isimmediately cancelled; therefore, the following is not caused: a strongelectric field is created between the piezoelectric thread line and theelectroconductive thread lines, or between the piezoelectric thread lineand any one of the other piezoelectric thread lines. Consequently, nocuring effect is exhibited.

(2) Piezoelectric Thread for Substance-Adsorption

As described above, when external force is applied to the piezoelectricthread 1, the thread generates negative charges. When external force isapplied to the piezoelectric thread 2, the thread generates positivecharges. Thus, the piezoelectric thread 1 has a nature of adsorbing asubstance having positive charges (such as particles of, for example,pollen), and the piezoelectric thread 2 has a nature of adsorbing asubstance having negative charges (such as a harmful substance, forexample, yellow sand). Accordingly, when the cloth having thepiezoelectric thread 1 or 2 is applied to, for example, a medicalarticle such as a face mask, this cloth-applied article can adsorb fineparticles of pollen or yellow sand. WO 2015/159832 publicly discloses atransducer in which a plurality of piezoelectric thread lines and aplurality of electroconductive thread lines are used to produce aknitting or woven fabric, and the fact that a displacement is given tothis knitting or fabric is sensed. In this case, all theelectroconductive thread lines are connected to a detecting sensor. Forany one of the piezoelectric thread lines, paired electroconductivethread lines, out of the electroconductive thread lines, are inevitablypresent. When electric charges are generated in the piezoelectric threadline, the electric charges are shifted in the electroconductive threadlines to neutralize the generated electric charges immediately. Thedetecting circuit detects an electric current based on this electronshift to output a signal. Accordingly, in this case, the generatedpotential is immediately cancelled; therefore, the following is notcaused: a strong electric field is created between the piezoelectricthread line and the electroconductive thread lines, or between thepiezoelectric thread line and any one of the other piezoelectric threadlines. Consequently, no adsorbing effect is exhibited.

Next, FIG. 6(A) is a schematic plan view of a cloth 100A, and FIG. 6(B)is a view illustrating an electric field generated between individuallines of threads. The respective directions of all arrows in an electricfield in FIG. 6B are reversed (a detailed description of which is setforth below).

In the cloth 100A illustrated in FIGS. 6(A) and 6(B), lines of apiezoelectric thread (first thread) 1, lines of a piezoelectric thread(second thread) 2, and lines of an ordinary thread 3 are woven into eachother. The ordinary thread 3 is a thread to which a piezoelectricsubstance is not fitted, and corresponds to a dielectric substance.

In the example in FIG. 6(B), the lines of the piezoelectric thread(first thread) 1, those of the piezoelectric thread (second thread) 2,and those of the ordinary thread 3 are arranged in parallel with eachother. The lines of the piezoelectric thread 1 are arranged, by apredetermined distance, apart from those of the piezoelectric thread 2to interpose therebetween one or more of those of the ordinary thread 3,which corresponds to a dielectric substance. The piezoelectric thread 1is different in the polarity of generated charges from the piezoelectricthread 2. A difference in electric potential between individual spotsthereof is defined by an electric-field-bonding circuit formed by thematter that the lines are complicatedly entangled with each other, ordefined by a circuit made of a current path formed incidentally in thethread lines by, for example, water content. Accordingly, when externalforce is applied to the lines of the threads, an electric fieldrepresented by outlined arrows in FIG. 6(B) is generated between thelines of the piezoelectric thread 2 generating positive charges andthose of the piezoelectric thread 1 generating negative charges.However, the ordinary thread 3 is not an essential constituent. Evenwhen the ordinary thread 3 is not used, an electric field is generatedbetween the lines of the piezoelectric thread 1 and those of thepiezoelectric thread 2. In a case where the piezoelectric thread 1 (Sthread) and the piezoelectric thread 2 (Z thread) are made of PLLA, atthe time of applying tension to the piezoelectric thread 1 alone, thesurface thereof turns negative in potential and the inside thereof turnspositive in potential. Conversely, at the time of applying tension tothe piezoelectric thread 2 alone, the surface thereof turns positive inpotential and the inside thereof turns negative in potential. When thesethreads approach or contact each other, their approach or contactregions (surfaces) turn to the same potential. In this case, thepotential of the approach or contact regions (surfaces) of thepiezoelectric threads 1 and 2 becomes 0 V, and the positive potential ofthe inside of the piezoelectric thread 1 becomes higher to keep theoriginal potential difference. In the same way, the negative potentialof the inside of the piezoelectric thread 2 becomes lower. In any crosssection of the piezoelectric thread 1, an electric field is created tobe directed mainly outward from the center of the cross section. In anycross section of the piezoelectric thread 2, an electric field iscreated to be directed mainly inward from the center of the crosssection. In spaces around these threads, leakage electric fields arecreated. These leakage electric fields are bonded to each other tocreate a strong electric field between the piezoelectric threads 1 and2.

The lines of the piezoelectric thread 1 are arranged very closely tothose of the piezoelectric thread 2 so that the distance therebetween isapproximately zero. The intensity of any electric field, as isrepresented by E=V/d, becomes larger in inverse proportion to thedistance between the substances generating charges. Thus, the intensityof the electric field generated by the cloth 100A becomes a very largevalue. This electric field is created by mutual bonding between electricfields generated inside the lines of the piezoelectric thread 1 andelectric fields generated inside lines of the piezoelectric thread 2. Asthe case may be, by water content containing an electrolyte such assweat, a circuit may be formed as an actual current path. In a cloth inwhich filaments of a fiber are knitted, fiber filaments arecomplicatedly entangled with each other, so that a case may be generatedwhere an electric field generated in one portion of the lines of thepiezoelectric thread 1 is mutually bonded to an electric field generatedin another portion of those of the piezoelectric thread 1. In the samemanner, a case may be generated where an electric field generated in oneportion of the lines of the piezoelectric thread 2 is mutually bonded toan electric field generated in another portion of those of thepiezoelectric thread 2. Even when the intensity of the electric field ismacroscopically zero or very weak, the electric field may bemicroscopically an aggregate of intense electric fields having vectordirections reverse to each other. About these phenomena, substantiallythe same description can be made even in a cloth made only of thepiezoelectric thread 1, a cloth made only of the piezoelectric thread 2,or a cloth made by weaving, into the piezoelectric thread 1 and/or 2, anordinary thread or electroconductive thread simultaneously.

Thus, the cloth 100A functions as a cloth generating an electric field.In the cloth 100A, a current may flow between the lines of thepiezoelectric thread 1 and the lines of the piezoelectric thread 2through water content such as sweat. By this electric field or current,the cloth may directly exhibit an antibacterial effect or sterilizingeffect. Alternatively, the cloth may indirectly exhibit an antibacterialeffect or sterilizing effect through active oxygen species obtained by achange of oxygen contained in water content by effect of the current orvoltage, and through active oxygen species or other antibacterialchemical species (such as amine derivatives) generated by interactionwith an additive contained in the fiber or by a catalytic effect.Alternatively, oxygen radials may be produced in cells of bacteria by astress environment based on the presence of the electric field orcurrent. In this way, an antibacterial effect or sterilizing effect maybe indirectly exhibited.

As this example, an example has been described in which thepiezoelectric thread 1 is different in the polarity of generated chargesfrom the piezoelectric thread 2. However, even when piezoelectricthreads having the same polarity are used, an electric field isgenerated or a current flows when an electric potential differenceexists in the space. Alternatively, an electric current flows through anelectroconductive medium therebetween.

The cloth 100A exhibits an antibacterial effect or sterilizing effect byan electric field which the cloth itself generates and a change in theintensity thereof, or by the current. Alternatively, the cloth exhibitsan antibacterial effect or sterilizing effect by, for example, radicalspecies generated by effect of the current or voltage. The cloth 100Amay also have an electroconductive fiber that elutes out therefrom ametal ion. In this case, in the cloth 100A, in addition to anantibacterial effect or sterilizing effect by the electric field, theantibacterial effect or sterilizing effect is further heightened by themetal ion eluted out from the electroconductive thread 5. About thecloth 100A, even when the piezoelectric thread 1 has a spot where nocharge is generated, this cloth exhibits an antibacterial effect orsterilizing effect through the metal ion eluted out from theelectroconductive thread 5.

A clothing article using the cloth 100A or a medical member using thisclothing article exhibits an antibacterial effect or sterilizing effectin the same manner. The clothing article using the cloth 100A,particularly, socks (or supporters) using the same also produce aremarkable advantageous effect for bacterium-countermeasure as describedabove. In the same manner as the above-mentioned piezoelectric threadthat acts on a living body or the piezoelectric thread forsubstance-adsorption, the cloth 100A also functions as a piezoelectriccloth that acts on a living body or a piezoelectric cloth forsubstance-adsorption.

The cloth 100A exhibits an antibacterial effect or sterilizing effectthrough an electric field or current generated by the piezoelectricthreads 1 and 2, which constitute this cloth itself, so that this clothexhibits an antibacterial effect or sterilizing effect against bacteriashifted to the cloth 100A. Bacteria which cause offensive odor wouldlive in gaps between fibers of the cloth. The cloth 100A can effectivelyexterminate such bacteria. On the skin of a human body, normal bacterialflora is present, which fulfills a role necessary for keeping the skinsurface in a normal state. However, small is the possibility that thecloth 100A directly kills the normal bacterial flora to produce only asmall risk of affecting the normal bacterial flora on the skin. Thus,the cloth is higher in safety.

As illustrated in FIG. 7, even in the cloth 100 A which is an embodimentin which lines of a piezoelectric thread 1, lines of a piezoelectricthread 2, and lines of an ordinary thread 3 are arranged to cross eachother, electric fields are generated in positions where the lines of thepiezoelectric thread 1 cross those of the piezoelectric thread 2.

In the above-mentioned examples, the descriptions have been made about acloth (woven fabric) in which plural threads including acharge-generating thread are woven into each other. However, also in acloth made of a knitted good (product in which rings made of pluralthreads including a charge-generating thread are hooked or hung witheach other), electric fields are generated or a current flows in thesame manner between lines of the threads in which an electric potentialdifference is generated. Thus, the knitted good produces anantibacterial effect or sterilizing effect.

In the present embodiment, as the example of the piezoelectricsubstance, a piezoelectric film has been described. However, thepiezoelectric substance may be a product obtained by, for example,jetting out a piezoelectric material into a yarn from a nozzle, and thendrawing the yarn (piezoelectric thread having a substantially circularsectional shape or a deformed sectional shape). A spinning methodtherefor may be, for example, wet spinning, dry spinning or meltspinning. For example, a polylactic acid (PLLA) piezoelectric thread isproduced through melt spinning, highly drawing treatment, and thermaltreatment (for crystallization). Also in the case of forming such athread (multifilament thread) in which lines of a PLLA piezoelectricthread are twisted with each other and further applying tension to thistread, the following is caused: in an S thread as this thread, on itssurface, negative charges are generated; and in a Z thread as thethread, on its surface, positive charges are generated. Such a threadcan be merely rendered a twisted thread without using any core thread.Such a thread can be produced at low costs. The number of filaments ofthe multifilament is a design item which should be designed in light ofthe use of the thread. The number of times of the twisting is also adesign item which should be appropriately designed. The filaments mayeach partially contain therein a filament which is not any piezoelectricsubstance. Moreover, the respective thicknesses of the filaments may notbe uniform. Such modifications cause a deviation in a potentialdistribution generated in any cross section of the thread to breaksymmetry therein. Thus, between the S thread as the thread and the Zthread as the thread, an electric field is easily created.

Next, FIG. 8(A) is a partial exploded view illustrating a structure of apiezoelectric thread 31, and FIG. 8(B) is a partial exploded viewillustrating a structure of a piezoelectric thread 32.

In the piezoelectric thread 31, a piezoelectric film 10 is further woundon a piezoelectric covering thread 1A that is an S thread. In thepiezoelectric thread 32, a piezoelectric film 10 is further wound on apiezoelectric covering thread 2A that is a Z thread. The piezoelectricthread 31 is a leftward spiraled thread (S thread) in which thepiezoelectric film 10 is leftward spiraled onto the piezoelectriccovering thread 1A. A drawn direction 900 thereof is in the state ofbeing leftward inclined at an angle of 45 degrees to the axial directionof the piezoelectric thread 31. The drawn direction 900 is consistentwith a drawn direction 900A of the piezoelectric covering thread 1A. Thepiezoelectric covering threads 1A and 2A may each a twisted threadhaving no core thread. A core thread of the thread 1A or 2A may be anelectroconductive thread.

When the piezoelectric thread 31 is pulled in the axis direction thereof(when external force is applied thereto), negative charges are generatedon the front surface of the piezoelectric covering thread 1A. In themeantime, positive charges are generated on the rear surface of thepiezoelectric film 10, which is opposite to the front surface of thepiezoelectric covering thread 1A. A difference in electric potentialbetween individual spots thereof is defined by an electric-field-bondingcircuit formed by the matter that lines of the thread are complicatedlyentangled with each other, or defined by a circuit made of a currentpath formed incidentally in the thread lines by effect of, for examplewater content. When the circuit has been formed, the intensity of theelectric field becomes larger in inverse proportion to the distancebetween the substances generating charges, so that the intensity of theelectric field becomes very high, the field being generated between thefront surface of the piezoelectric covering thread 1A and the rearsurface of the piezoelectric film 10. In short, this structure makes theantibacterial effect or sterilizing effect of the thread itself higher.When the piezoelectric thread 31 is pulled in the axis direction thereof(when external force is applied thereto), negative charges are generatedon the front surface of the piezoelectric thread 31 (the front surfaceof the piezoelectric film 10). Thus, by combining this thread 31 with athread having a surface in which positive charges are generated, anelectric field can also be further generated between the threads.

In the meantime, as illustrated in FIG. 8(B), the piezoelectric thread32 is a right spiraled thread (Z thread) in which the piezoelectric film10 is rightward spiraled onto the piezoelectric covering thread 2A. Adrawn direction 900 thereof is in the state of being rightward inclinedat an angle of 45 degrees to the axial direction of the piezoelectricthread 31. The drawn direction 900 is consistent with a drawn direction900A of the piezoelectric covering thread 2A.

When the piezoelectric thread 32 is pulled in the axis direction thereof(when external force is applied thereto), positive charges are generatedon the front surface of the piezoelectric covering thread 2A (the frontsurface of the piezoelectric film 10). Negative charges are generated onthe rear surface of the piezoelectric film 10, which is opposite to thefront surface of the piezoelectric covering thread 2A. A difference inelectric potential between individual spots thereof is defined by acircuit formed by the matter that lines of the thread are complicatedlyentangled with each other, or defined by a circuit made of a currentpath formed incidentally in the thread lines by, for example, watercontent. When the circuit has been formed, the intensity of the electricfield becomes larger in inverse proportion to the distance between thesubstances generating charges, so that the intensity of the electricfield becomes very high, the field being generated between the frontsurface of the piezoelectric covering thread 2A and the rear surface ofthe piezoelectric film 10. In short, in the same manner as the structureof the piezoelectric thread 31, this structure makes the antibacterialeffect or sterilizing effect of the thread itself higher. When thepiezoelectric thread 32 is pulled in the axis direction thereof (whenexternal force is applied thereto), positive charges are generated onthe front surface of the piezoelectric thread 32 (the front surface ofthe piezoelectric film 10A). Thus, in the same manner as in thepiezoelectric thread 31, by combining this thread 32 with a threadhaving a surface in which negative charges are generated, an electricfield can also be generated between the threads.

Next, FIG. 9(A) is a partial exploded view illustrating a structure of apiezoelectric thread 33, and FIG. 9(B) is a partial exploded viewillustrating a structure of a piezoelectric thread 34.

In the piezoelectric thread 33, a piezoelectric film 10 is wound on apiezoelectric covering thread 1A. In the piezoelectric thread 34, apiezoelectric film 10 is wound on a piezoelectric covering thread 2A.

The piezoelectric thread 33 is a rightward spiraled thread (Z thread) inwhich the piezoelectric film 10 is rightward spiraled onto thepiezoelectric covering thread 1A. A drawn direction 900 thereof is inthe state of being rightward inclined at an angle of 45 degrees to theaxial direction of the piezoelectric thread 33. The drawn direction 900is different from a drawn direction 900A of the piezoelectric coveringthread 1A.

As illustrated in FIG. 9(B), the piezoelectric thread 34 is a leftwardspiraled thread (S thread) in which the piezoelectric film 10 isleftward spiraled onto the piezoelectric covering thread 2A. A drawndirection 900 thereof is in the state of being leftward inclined at anangle of 45 degrees to the axial direction of the piezoelectric thread34. The drawn direction 900 is different from a drawn direction 900A ofthe piezoelectric covering thread 2A.

FIG. 10 is a view illustrating a gap between portions of thepiezoelectric film 10 exaggeratedly in the piezoelectric thread 33. Whenthe piezoelectric film 10 is wound onto the covering thread in thepiezoelectric thread 33, the gap, which is a gap D, is generated to somedegree. When the piezoelectric thread 33 is pulled in the drawndirection thereof, this gap D causes the generation of an electric fieldbetween the surface of the piezoelectric covering thread 1A and thesurface of the piezoelectric film 10 to form a circuit. Thus, thisstructure heightens the antibacterial effect or sterilizing effect ofthe thread itself. The same matter is applied to piezoelectric thread34.

In the piezoelectric thread 33, in the case of using PDLA for any one ofthe piezoelectric covering thread 1A and the piezoelectric film 10, thepiezoelectric thread 33 comes to have the same structure as thepiezoelectric thread 31 because the front surface of the piezoelectriccovering thread 1A is different in the polarity of generated chargesfrom the rear surface of the piezoelectric film 10. Thus, an intenseelectric field is generated between the front surface of thepiezoelectric covering thread 1A and the rear surface of thepiezoelectric film 10. This matter is applied, in the piezoelectricthread 34, to the case of using PDLA for any one of the piezoelectriccovering thread 2A and the piezoelectric film 10.

Next, FIG. 11 is a partial exploded view illustrating a structure of apiezoelectric thread 35. The piezoelectric thread 35 is a thread (Sthread) obtained by spiraling a line of the piezoelectric thread 1 and aline of the piezoelectric thread 2 leftward to be twisted with eachother. The piezoelectric thread 35 is obtained by causing the line ofthe piezoelectric thread 1 having a surface in which negative chargesare generated to cross the line of the piezoelectric thread 2 having asurface in which positive charges are generated. Thus, the thread cansingly generate an electric field. As described above, the potentialsgenerated, respectively, in the surface of the piezoelectric thread 1and in that of the piezoelectric thread 2 forcibly become equal to eachother in their approach and contact regions of the surfaces.

Correspondingly, the potentials of the thread insides are changed tokeep a difference in potential between the surfaces of the threads andthe insides thereof. In each of the threads, an electric field createdbetween the thread surface and the thread inside leaks out into the air.The electric fields of the threads are bonded to each other so that astrong electric field is created in the approach and contact regions ofthe piezoelectric threads 1 and 2. Such twisted threads have acomplicated structure. Thus, the approach and contact regions of thepiezoelectric threads 1 and 2 are not uniform. When tension is appliedto the approach and contact regions, these regions are also changed. Asa result of this change, in each of the regions, the electric field ischanged in intensity, so that the symmetry of the electric fields isbroken.

Consequently, an electric field circuit is generated. Also in a thread(Z thread) obtained by spiraling a line of the piezoelectric thread 1and a line of the piezoelectric thread 2 rightward to be twisted witheach other, the line of the piezoelectric thread 1, which has a surfacein which negative charges are generated, crosses the line of thepiezoelectric thread 2, which has a surface in which positive chargesare generated, so that the Z thread can singly generate an electricfield. The number of times of the twisting of the piezoelectric thread1, that of the piezoelectric thread 2, and that of the twisted thread 35produced by twisting the piezoelectric threads 1 and 2 with each otherare each a design item which should be determined in light of theantibacterial effect of these threads. All of the application examplesthat have been demonstrated hereinbefore can be configured by using thepiezoelectric thread 35.

Also, A trilayered covering thread can singly generate an electricfield, this thread being a thread in which an ordinary thread is twistedon the side surface of an S thread (or Z thread) and further a Z thread(or S thread) is twisted on the side surface of the ordinary thread.

FIG. 12 illustrates a thread (third thread) made of a braid obtained byforming, at the same time, a piezoelectric thread 1 spiraled rightward(or leftward) onto the surface of an ordinary thread, and apiezoelectric thread 2 spiraled leftward (or rightward) onto the surfaceof the ordinary thread. As illustrated in this figure, also in thisthird thread, respective electric fields are generated at spots wherethe piezoelectric thread 1 crosses the piezoelectric thread 2, so thatthe third thread can singly generate an electric field.

It is also conceivable that a thread having a surface in which negativecharges are generated is, besides an S thread using PLLA, a Z threadusing PDLA. It is also conceivable that a thread having a surface inwhich positive charges are generated is, besides a Z thread using PLLA,an S thread using PDLA. Accordingly, in the same structure asillustrated in FIG. 11, the following piezoelectric thread can alsosingly generate an electric field: a piezoelectric thread made of athread (S thread) obtained by spiraling an S thread using PLLA and an Sthread using PDLA leftward to be twisted with each other, or made of athread (Z thread) obtained by spiraling the same threads rightward to betwisted with each other. The following piezoelectric thread can alsosingly generate an electric field: a piezoelectric thread made of athread (S thread) obtained by spiraling a Z thread using PLLA and a Zthread using PDLA leftward to be twisted with each other, or made of athread (Z thread) obtained by spiraling the same threads rightward to betwisted with each other.

The following will describe an antibacterial effect of threads each madeof a piezoelectric substance. The present inventors made quantitativetests (1) and (2) described below to evaluate a bacteria inhibitingeffect of a cloth in which threads each made of a piezoelectricsubstance were woven into each other.

(1) Evaluation of antibacterial effect of cloth in which threads eachmade of piezoelectric substance were woven into each other

a) Test method: bacterium liquid absorption method (JIS L1902),

b) Test bacterium: Staphylococcus aureus NBRC 12732,

c) Inoculated bacterium liquid concentration: 1.4×105 (CFU/mL),

d) Standard cloths: a cloth obtained by weaving cotton yarn, and a clothobtained by knitting cotton yarn, and

e) Test sample (sample subjected to antibacterial treatment): a clothobtained by knitting an S thread (piezoelectric thread 35) in which an Sthread (piezoelectric thread 1) and a Z thread (piezoelectric thread 2)were leftward spiraled to be twisted with each other.

[Calculating Expressions]

G=Mb−Ma  Proliferation value:

A=(Mb−Ma)−(Mc−Mo)  Antibacterial activity value:

The antibacterial activity value of ordinary products subjected toantibacterial treatment is as follows: antibacterial activity value A≥value of 2.0 to 2.2.

-   -   Ma: arithmetic average common logarithm of the respective        numbers of living bacteria (or the quantity of ATP) in three        specimens of each of the standard cloths immediately after the        inoculation of the test bacteria,    -   Mb: arithmetic average common logarithm of the respective        numbers of living bacteria (or the quantity of ATP) in the three        specimens of each of the standard cloths after the bacteria were        cultured for 18 to 24 hours, and    -   Mo: arithmetic average common logarithm of the respective        numbers of living bacteria (or the quantity of ATP) in three        specimens of the test sample (sample subjected to the        antibacterial treatment) immediately after the inoculation of        the test bacteria, and    -   Mc: arithmetic average common logarithm of the respective        numbers of living bacteria (or the quantity of ATP) in the three        specimens of the test sample (sample subjected to the        antibacterial treatment) after the bacteria were cultured for 18        to 24 hours.

TABLE 1 Anti- Arithmetic average common Pro- bacterial logarithm of thenumber of liferation activation Sample living bacteria value G value A(1) Standard Immediately after Ma = 4.35 2.5 Clothes (cotton,inoculation and woven After culturing for Mb = 6.83 product) 18 hours(2) Standard Immediately after Mo = 4.42 3.0 −0.5 on the Clothes(cotton, inoculation basis of and knitted After culturing for Mc = 7.45standard product) 18 hours (standing cloth still) After culturing for Mc= 6.39 2.0 0.5 18 hours (vibration) (3) Test sample Immediately after Mo= 4.43 1.4 1.6 on the (cloth obtained inoculation basis of (2) byknitting an After culturing for Mc = 5.80 S-twisted thread 18 hours(standing of S and Z still) threads) After culturing for Mc = 1.30 −3.15.1 18 hours (vibration)

As is evident from Table 1, the test sample (cloth in which the threadsmade of the piezoelectric substance are woven into each other) has ahigher antibacterial effect against the bacteria than the standardcloths. It is also understood that the test sample is higher inantibacterial effect when the test sample is vibrated than when allowedto stand still. In particular, when the test sample is vibrated togenerate an electric field, normal bacteria are hardly observed at atime after 18 hours from the inoculation of the test bacteria (bacilli).Thus, the sample exhibits a high antibacterial effect (sterilizingeffect).

(2) Evaluation of anti-mold property of cloth in which threads each madeof piezoelectric substance were woven into each other

a) Test method: anti-mold quantitative test method (method prescribed byJapan Textile Evaluation Technology Council),

b) Test bacteria: Aspergillus niger NBRC 105649,

c) Inoculated bacterium liquid concentration: 1.1×105 (CFU/mL),

d) Standard cloths: a cloth obtained by weaving cotton yarn, and a clothobtained by knitting cotton yarn, and

e) Test sample (sample subjected to antibacterial treatment): a clothobtained by knitting a piezoelectric thread (piezoelectric thread 35) inwhich an S thread (piezoelectric thread 1) and a Z thread (piezoelectricthread 2) were leftward spiraled to be twisted with each other.

[Calculating Expressions]

F=Fb−Fa  Growth value:

FS=(Fb−Fa)−(Fc−Fo)  Anti-mold activity value:

-   -   Fa: arithmetic average common logarithm of the respective        numbers of living bacteria (or the quantity of ATP) in three        specimens of each of the standard cloths immediately after the        inoculation of the test bacteria,    -   Fb: arithmetic average common logarithm of the respective        numbers of living bacteria (or the quantity of ATP) in the three        specimens of each of the standard cloths after the bacteria were        cultured for 42 hours, and    -   Fo: arithmetic average common logarithm of the respective        numbers of living bacteria (or the quantity of ATP) in three        specimens of the test sample (sample subjected to the        antibacterial treatment) immediately after the inoculation of        the test bacteria, and    -   Fc: arithmetic average common logarithm of the respective        numbers of living bacteria (or the quantity of ATP) in the three        specimens of the test sample (sample subjected to the        antibacterial treatment) after the bacteria were cultured for 42        hours.

TABLE 2 Arithmetic average common Growth Anti-mold logarithm of thenumber of value activity Sample living bacteria F value (1) StandardImmediately after Fa = −11.79 2.3 Clothes (cotton, inoculation and wovenAfter culturing for Fb = −9.50 product) 42 hours (2) StandardImmediately after Fo = −11.69 2.3 0.0 on the Clothes (cotton,inoculation basis of and knitted After culturing for Fc = −9.39 standardproduct) 42 hours (standing cloth still) After culturing for Fc = −10.471.2 1.1 42 hours (vibration) (3) Test sample Immediately after Fo =−11.79 1.5 0.7 on the (cloth obtained inoculation basis of (2) byknitting an After culturing for Fc = −10.15 S-twisted thread 42 hours(standing of S and Z still) threads) After culturing for Fc = −12.67−1.0 2.2 42 hours (vibration)

As is evident from Table 2, the test sample (cloth in which the threadsmade of the piezoelectric substance are woven into each other) also hasa higher anti-fungus effect against the fungi (such as mold) than thestandard cloths. It is also understood that the test sample is higher inanti-mold effect when the test sample is vibrated than when allowed tostand still. In other words, when the test sample is vibrated togenerate an electric field, the sample exhibits a high anti-mold effect.

The above-mentioned results have clearly demonstrated that a cloth intowhich a thread made of a piezoelectric substance is woven hasantibacterial property and anti-molding property.

Other examples of the charge-generating fiber which generates a chargeby an energy from the outside include a substance having photoelectriceffect, a substance having pyroelectric effect (such as PVDF), and asubstance which generates a charge by chemical reaction. The followingstructure also forms a charge-generating fiber: a structure in which anelectroconductive body is used as a core thread, an insulator is woundon the electroconductive body, and further electricity is caused to flowin the electroconductive body. The piezoelectric substance generates anelectric field through piezoelectricity, so that no power source isrequired and no electric shock is favorably caused. Moreover, thelifespan of the piezoelectric substance is sustained longer than theperiod of an antibacterial effect of any chemical agent or the like.Furthermore, the piezoelectric substance is less likely to cause a riskof generating an allergenic reaction than any chemical agent. In recentyears, a serious problem is the generation of bacteria resistant tochemicals, in particular, antibiotics or the like. However, it is notbelieved that the sterilizing method of the present invention causes thegeneration of resistant bacteria due to the mechanism of providing theantibacterial effect.

Lastly, it should be interpreted that the description on the presentembodiment is a description on examples in all respects and is notrestrictive. The scope of the present invention is not described in theembodiment, but recited in the claims. Furthermore, it is intended thatthe scope of the invention includes all variations within meanings andscopes equivalent to the claims.

DESCRIPTION OF REFERENCE SYMBOLS

-   -   1, 2: Piezoelectric thread    -   1A, 2A: Piezoelectric covering thread    -   3: Ordinary thread    -   5: Electroconductive thread    -   10: Piezoelectric film    -   11: Core thread    -   100, 100A: Cloth    -   900: Drawn direction    -   910A: First diagonal line    -   910B: Second diagonal line

1. A piezoelectric thread comprising: a core thread; and a piezoelectricfilm wound around the core thread, wherein the piezoelectric thread isconstructed to generate a charge by energy imparted from outside of thepiezoelectric thread.
 2. The piezoelectric thread according to claim 1,wherein the piezoelectric film comprises polylactic acid.
 3. Thepiezoelectric thread according to claim 2, wherein the core threadcomprises a natural or chemical fiber.
 4. The piezoelectric threadaccording to claim 3, wherein the core thread comprises polylactic acid.5. The piezoelectric thread according to claim 1, wherein the corethread comprises a natural or chemical fiber.
 6. The piezoelectricthread according to claim 5, wherein the core thread comprisespolylactic acid.
 7. The piezoelectric thread according to claim 1,wherein the core thread is an electroconductive thread.
 8. Thepiezoelectric thread according to claim 1, wherein the piezoelectricfilm is a monoaxially drawn film, and the piezoelectric film is woundaround the core thread such that a drawn direction if the piezoelectricfilm is inclined relative to an axial direction of the piezoelectricthread.
 9. A cloth comprising a plurality of the piezoelectric threadsaccording to claim 1, the cloth having an antibacterial activity value Aof >2.2 after culturing for at least 18 hours while the plurality ofpiezoelectric threads generate a charge by the energy imparted from theoutside of the piezoelectric thread.
 10. The cloth according to claim 9,wherein the plurality of piezoelectric threads are in a wovenconfiguration, and the woven configuration is configured to generate anelectric field between a first thread and a second thread of theplurality of threads due to a difference in electric potentialtherebetween.
 11. The cloth according to claim 10, wherein the firstthread and the second thread are configured to generate a current due toa difference in electric potential between the first thread and thesecond thread.
 12. The cloth according to claim 10, wherein the firstthread generates a first charge that is different in polarity a secondcharge generated by the second thread.
 13. The cloth according to claim10, wherein, in the woven configuration, the first thread is arranged inparallel with the second thread.
 14. The cloth according to claim 10,wherein, in the woven configuration, the first thread is arranged tocross the second thread.
 15. The cloth according to claim 10, furthercomprising a third thread, and wherein the first thread, the secondthread, and the third thread are braided together.
 16. A clothingarticle comprising the cloth according to claim
 9. 17. A medical membercomprising the clothing article according to claim 16.